Hundreds of people swept through the Magnificent Mile and other parts of downtown Chicago early Monday, smashing windows, looting stores, confronting police and at one point exchanging gunfire with officers, authorities said.

More than 100 people were arrested as of 9 a.m., according to Chicago Police Superintendent David Brown. Thirteen officers were injured during the unrest, including a sergeant who was hit by a bottle. A civilian and private security guard were shot and wounded.

“What occurred in our downtown and surrounding communities was abject criminal behavior, pure and simple,” Mayor Lori Lightfoot said. “And there cannot be any excuse for it. Period.”

It took police officers roughly four hours to get the downtown back under control, leading to finger pointing across the political spectrum and calls for the Illinois National Guard to once again help quell unrest in the country’s third-largest city.

Downtown Ald. Brian Hopkins, who said he was on Michigan Avenue from midnight to 4 a.m., described a scene in which officers were overwhelmed by looters and apparently did not have much of a plan for restoring order. He criticized Lightfoot for failing to develop an effective strategy following recent looting incidents in May and June.

“The real question today is, where was the strategy? What was the decision making at the highest levels?” Hopkins said. “That means the police superintendent and the mayor, who’s a very hands-on mayor when it comes to these kinds of decisions.”

City officials said the seeds for the violent crime spree were sown on social media Sunday afternoon following an officer involved shooting in the Englewood neighborhood. Officers shot and wounded a 20-year-old man Sunday after he fired shots at them while being chased, authorities said.

The man was taken to University of Chicago Medical Center and is expected to survive, Brown said....